An Internet Protocol (IP) session involves the connection between two devices across a network of routers, cables, and switches for the purpose of exchanging packets of information. For example, a web browser can establish an IP-based Hypertext Transfer Protocol Secure (HTTPS) session with a website for the purpose of retrieving information. In another example, a device can establish a Session Initiation Protocol (SIP) session with another computing device to, e.g., conduct a phone call.
Web browsers have recently begun adopting the Web Real-Time Communication (WebRTC) protocol for the purpose of establishing real-time audio and video sessions between browser clients. WebRTC enables web browsers with Real-Time Communications (RTC) capabilities via simple JavaScript APIs. The web platform provides a way of viewing a wide variety of content, provides developers with a write-once deploy-everywhere model, and supports service providers in deploying services with global reach. Browser-technology enhancements, exemplified by HTML5, and the ongoing work to add real-time communication to the web platform create new opportunities for combining communication and data, and improving the user experience.
The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is an architectural framework for delivering IP multimedia services. IMS is based primarily on Session Initiation Protocol (SIP) as a rich, real-time media session protocol for IP networks, and as such, relies on SIP-based endpoints and soft-clients to register and support subscribers on the services. The IMS architecture is designed to separate the services offered by fixed-line (traditional telecommunications companies), mobile (traditional cellular), and converged service providers (cable companies and others who provide triple-play, e.g., voice, video, and data services) from the access networks used to receive those services.
An IMS capable terminal uses an application on the user equipment UE) to sends and receive SIP requests. However, an IMS capable terminal may be implemented as software on a PC, on an IP phone, etc. However, a WebRTC client enabled device, such as a UE, does not include IMS client capability and thus cannot access the IMS core.